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SPEC RESCUE – Oversimplifying Existing Glass

A man covering his eyes while trying to throw a dart.

When calculating energy savings from the application of window film, window film specs are important to consider. Learn more about calculating energy savings below.

Imagine you are trying to calculate savings from a lighting retrofit and the options for existing lighting were:

  • LED
  • Fluorescent
  • Metal Halide
  • LPS

These four are simple enough to distinguish from one another but are woefully inadequate within the category to calculate savings.

However, this is what almost every window film technology provider does when they consider the existing glass as:

  • Clear single pane
  • Clear double pane
  • Tinted single pane
  • Tinted double pane

Technology is readily available by Lawrence Berkeley Laboratory Window and Daylighting Group ( that allows anyone to calculate nearly 500,000 glass and window film specs combinations in about an hour.

Your client has real glass and real film combinations that will dramatically impact calculated ROI – don’t make the mistake of oversimplifying the glazing improvement.


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